This application claims priority to U.S. Patent Application Ser. No. 61/334,393, which was filed May 13, 2010. This priority application is hereby incorporated by reference in its entirety into the present application, to the extent that it is not inconsistent with the present application.
In subsea hydrocarbon production and transmission, it is possible to have a compressor system positioned in a remote location, i.e., subsea. These subsea compressor systems are generally powered by an electric motor connected to a centrifugal compressor that receives electrical power from a shore or platform-based electrical source. As such, the electrical power is supplied to the electric motor via an umbilical that extends from the electrical source to the remotely located compressor system. However, this configuration presents several challenges as the extended length of the umbilical leads to significant electrical line losses, e.g., up to two-thirds of the total power consumed in some cases. Furthermore, the large amount of power needed to power the high-speed motors that are often used in the compression field requires multiple and/or heavy gauge wires, thereby requiring a large diameter conduit, umbilical cord, or cable, which has a significant cost implication, i.e., millions of dollars per mile. Additionally, servicing or maintaining the electric motor and an accompanying electric switchgear becomes a significant challenge in remote installations, especially in hostile environments like subsea applications.
What is needed, therefore, is an efficient apparatus and method for compressing gas at a remote location, including subsea locations, that does not suffer from these and other drawbacks inherent in conventional systems.